Annona squamosa also known as Custard apple, Sugar-apple or Sweetsop, belongs to Annonaceae family and native to the tropical Americas. Annona squamosa is a shrub or small tree up to 6 m height. Custard apple is an edible fruit with white pulp that contains many black shiny seeds in it. It is commonly found in deciduous forests and also being cultivated in many parts of India. Pulp of the fruit is eaten fresh or converted into juice or shake. Fruits are normally eaten fresh. Its exact native range is unknown due to extensive cultivation, but thought to be in the Caribbean; the species was described from Jamaica.
Some of the phytochemistry of Annona squamosa is as follows. The volatile constituents of Annona squamosa L. bark were identified from the essential oil obtained by steam distillation. Six major components were identified as 1H-Cycloprop(e)azulene (3.46%), germacrene D (11.44%), bisabolene (4.48%), caryophyllene oxide (29.38%), bisabolene epoxide (3.64%) and kaur-16-ene (19.13%) were identified by studied by GC/MS.
Eleven annonaceous acetogenins compounds were isolated and identified as squamocenin, annotemoyin-2, reticulatain-2, squamocin-I, squamocin-B, squamocin, motrilin, squamostatin-D, squamostatin-E, cherimolin-1 and cherimolin-2 from the ethyl alcohol extract of A. squamosa L seeds.
Annonaceous acetogenins are a well-established class of natural compounds that have been isolated from plants in the Annonaceae family. Tetrahydrofuranic acetogenins are a prominent class among them [Feras, Q. A., et. al., J. Nat. Prod., 1999, 62: 504-540]. It has been reported that various members of this class of compounds exhibit significant bioactivities. Acetogenins are C35-C39 compounds that typically contain two long hydrocarbon chains, one of which connects a terminal 2,4-disubstituted-γ-lactone to a variable number of tetrahydrofuran (THF) rings. The hydrocarbon chains contain a number of oxygenated moieties which can be hydroxyls, acetoxyls and/or ketones. Recently, single-ring acetogenins containing double bonds, epoxide compounds which lack THF rings and a compound lacking both epoxides and THF rings have been reported. These compounds support the proposed polyketide origin of the Annonaceous acetogenins.
Leaves of Annona squamosa were found to have mosquito insecticide properties and used for treating sleeping sickness. The crushed seeds were found to have insecticidal properties against fruit flies and lice. The fruit pulp contains vitamin C and is good for teeth, bones, skin and muscle. The flowers have been used to treat eye inflammation. Paste of seed powder is used to treat head lice and used in cancer treatment. The bark extract is used to treat skin diseases and control intestinal worms. The root extract is used to treat cancerous tumors. [A. C. de Q. Pinto, Field Manual for extension workers and farmers, Practical manual no. 5, 2006].
Some of the pharmacological activities of Annona squamosa are summarized below:
Cyclosquamosin D isolated from the seeds of Annona squamosa showed anti-inflammatory activity by inhibiting the production of pro-inflammatory cytokines within lipopolysaccharide and Pam3Cys-stimulated J774A.1 macrophages. [Yang, Y. L., et al., J Agric Food Chem. 2008, 56: 386-92].
Some of the active compounds isolated from Annona squamosa seed showed anti-head lice effect. [Junya Intaranongpai et al., Southeast Asian J. Trop. Med. Public Health, 2006, 37: pages]. Roots of Annona squamosa are known for the management of constipation. The hepatoprotective activity [Mohamed Saleem T S et al., International Journal of Applied Research in Natural Products, 2008, 1: 1-7.] was also reported for Annona squamosa. 
Reactive oxygen species (ROS) and granule proteases produced by neutrophils contribute to the pathogenesis of inflammatory diseases. An ent-kurane compound 16-beta,17-dihydroxy-ent-kauran-19-oic acid isolated from the stems of Annona squamosa exhibited potent immunomodulating effects in leukocytes and anti-inflammatory activity through the inhibition of the generation of superoxide anion, the formation of ROS, and the release of elastase in formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-activated human neutrophils.
In another research study, the Caryophyllene oxide isolated from Annona squamosa at the doses of 12.5 and 25 mg/kg body wt. showed significant central as well as peripheral analgesic activity, along with anti-inflammatory activity. [Chavan, M. J., et al., Phytomedicine. 2009].
The anti-inflammatory activity of Annona squamosa was reported earlier in an Indian Patent application 2756/DEL/2006. The application describes a process of preparing an extract of Annona squamosa comprising the active compounds 16-Hydroxyoctadeca-9(Z or E), 12 (Z or E), 14(Z or E)-trienoic acid and 13-Hydroxy-9Z-11E-15E-octadecatrienoic acid and its use for the treatment of cancer, diabetes and related complications including inflammatory conditions such as AIDS, asthma, arthritis, bronchitis, chronic obstructive pulmonary disease (COPD), psoriasis, allergic rhinitis, shock, atopic dermatitis, Crohn's disease, adult respiratory distress syndrome (ARDS), eosinophilic granuloma, allergic conjunctivitis, osteoarthritis or ulcerative colitis. The trienoic acid compounds were attributed to be responsible for the activity.
Chinese patent application CN1477102 relates to sugar apple plant extract with the action of resisting diabetes, its application and preparation method. The raw material is extracted from branch, leaf, trunk, bark, root, seed and fruit skin of Annona squamosa plant. The acetogenin compounds can be made into various dosage forms for curing diabetes, and its preparation method can adopt one or several processes of solvent extraction process, resin adsorption process, supercritical CO2 extraction process and conventional drying process.
U.S. Pat. No. 6,242,483 relates to the isolation of three new mono-tetrahydrofuran ring acetogenins from the bark of Annona squamosa. Each of these compounds bears a carbonyl group at the C-9 position and two hydroxyls that flank the tetrahydrofuran ring. These compounds exhibit selective cytotoxic activity against certain specific human tumor cells.